Abstract:

Objective To evaluate the effect and safety of long-term wearing high precision ORTHO-K contact lens for myopic children and adolescents. Design Retrospective case series. Participants 150 myopic children and adolescents. Methods We examined 150 patients ( 300 eyes) who wore ORTHO-K lens for 3 years in Beijing Internet Eyecare Optometry ＆ Ophthalmology Clinic. Following examinations had been performed for baseline and all annual follow-up visits: slit lamp exam, uncorrected visual acuity(UCVA), and tear secretion, eye axial length, corneal thickness, corneal endothelial cell density, percentage of hexagon and corneal curvature values. We also selected 66 eyes switching to ORTHO-K from other brands for evaluation of comfort, clarity and cleanliness. Main Outcome Measures The UCVA corneal endothelial cell density, percentage of hexagon cells, axial length, tear secretion, corneal thickness, and corneal conjunctival health condition. Results No obvious adverse reaction was found on the cornea and conjunctival. The UCVA improved significantly (4.55 ±0.34 before wearing vs. 4.88±0.25 after three years, P<0.001). The refractive error decreased during early wearing period. The spherical and cylindrical diopters were (-2.99±2.44) D and (-1.17±1.20) D at baseline; which decreased to (-1.95±2.12) D and (-1.11±1.06) D respectively after initial wearing stage (P=0.01, P=0.001). The axial length increased slightly but not significantly (0.28±0.12) mm after three years. The corneal thickness decreased by (-7.71±2.88) μm, (-2.56±2.78) μm and (0.44±2.95) μm at one, two and three year respectively, reaching to a significant thinning at 3 year compared to baseline (P=0.001). The endothelial cell density was（3244±309）pieces /mm², （3265±304)pieces /mm², (3264±299)pieces/mm², (3270±296)pieces/mm² at baseline, year 1, year 2 and year 3 respectively (all P>0.05). There was no significant change on tear secretion. The scores of comfort, clarity, cleanliness of the original type of lenses were 8.69±0.62, 9.26±0.72, 9.37±0.58, which improved significantly to 9.16±0.36, 9.33±0.65, 9.62±0.47 respectively （t=-2.181，-0.601，-0.830; all P<0.05） after switching to high precision type.  Conclusion The result of 3 years follow-up shows that the subjective comfort improved after switching to high precision lens. Wearing high precision ORTHO-K lens enhanced unaided vision acuity and showed myopia control effects. With regular and scientific fitting, ocular surface would remain unaffected. （Ophthalmol CHN， 2018, 27： 353-357）

Key words:  orthokeratology, myopia, myopia control, axial length